1. Why Are You So Tense Compression (squeeze) Tension (stretch) I – Beams
Occurs when Atoms are being pushed together
Tension (stretch)
Occurs when Atoms are being pulled apart
I – Beams
Demonstrate with a piece of paper, weak, then fold it – stronger Straw into potato?
Some only 1 or other concrete, steel, paper – reinforced concrete
I – Beam look around the room and see how many you can see
NTQ after this slide

2. Problems for those who use this stuff
Live, Dead loads
Library (Purdue)
Tacoma Narrows Bridge
Harmonic Resonance
September 11th – live vs. dead load
Urban Legend about college library
Tacoma Narrow’s Bridge

3. Scaling, Scaling over the ocean blue
Find surface area and volume for cubes of side length 1,2,3 and 4 centimeters
As size increases, V grows faster than S.A.
Elephant ears, French fries, Falling bugs, cells
Have them do the cubes – complete chart on the board
Coal dust and explosions (ca-boom video from chem – flour bomb)
Starting a fire – what do you use (big chunk vs. shavings)